The present invention relates to a vehicle for providing power to a plurality of power driven plant trimming tools, and more particularly to a self-propelled, self-steered vehicle that is adapted to steer itself automatically and draw a telescopic boom through a cultivated field, the boom including air lines for feeding compressed air to a plurality of manually controlled, pneumatically operated pruning devices. The invention also relates to an arrangement for removing moisture from air so that the formation of ice in the air lines is avoided.